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Home >> Mercedes Benz >> 1990 >> 420SEL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Engine Sensors & Switches >> Hall Effect Speed Sensor (190E 2.6L) Test

Hall Effect Speed Sensor (190E 2.6L) Test

  1. The speed signal switches engine idle speed control over to airflow control at vehicle speeds greater than 9 MPH. This improves driveability at slow stop-and-go speeds. Engine idle speed control is activated again at vehicle speed less than 7 MPH.
  2. Turn ignition off. Disconnect CIS-E control unit plug (located under dash on passenger's side). Turn ignition on. Measure voltage on CIS-E control unit plug between socket Nos. 1 and 6. Push vehicle approximately 3 feet. Reading should oscillate between 0 and 12 volts. If response is as specified, go to next step. If reading does not oscillate as specified, repair open circuit. If necessary, replace Hall Effect speed sensor.
  3. Connect CIS-E control unit plug. Connect On-Off Ratio Tester (KDJE-P 600) to diagnostic socket. Drive in 3rd gear (position "3") on dynamometer or open road. At approximately 2000 RPM, accelerate at full throttle for approximately 6 seconds. If tester needle oscillates after releasing accelerator pedal, test results are okay. If on-off ratio is 60% constant, replace CIS-E control unit.
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